需要幫助調試，新的節目

Question

這個代碼並且不能進行調試工作，有什麼它應該做的是寫在評論任何想法。感謝所有快速回答的人。任何幫助都會很棒。

/* 
     Debugging: Speed 
     When corrected, this program accepts an int value for starting mileage, an int value for ending mileage, a double value for time of travel, and then performs the calcualtion necessary to output the miles per hour. The program should exit (quit) after the last window is closed. 
    */ 

    public class Speed 
    { 
     public static void main(String[] args) 
     { 
      //Declare Class Variables 
      String highway; 
      int startMiles=0; 
      double endMiles=0; 
      double time= 0; 
      boolean done = false; 

      while (done) 
      { 
       try 
       { 
        String start = JOptionPane.showInputDialog(null,"Enter starting mileage: "); 
        startMiles = Integer.parseInt(start); 

        String end =JOptionPane.showInputDialog(null,"Enter ending mileage: "); 
        endMiles = Integer.parseInt(end); 

        if (endMiles<=startMiles) throw new Exception(); 

        String amount = JOptionPane.showInputDialog(null,"Enter total time as a decimal value: "); 
        gallons = Integer.parseInt(amount); 
        done = true; 
       } 
       catch(Exception e) 
       { 
        JOptionPane.showMessageDialog(null, "Your ending mileage,",endMiles +", must be greater than your starting mileage, " + startMiles, "Error in Mileage", JOptionPane.ERROR_MESSAGE); 
       } 
      } 
      JOptionPane.showMessageDialog(null,"Average speed is "+ (endMiles - startMiles)/time +"miles per hour."); 
     } 
    } 

Answer 1

這是一個問題。

boolean done = false; 

    while (done){ 
     -- As Done is false nothing in here will ever run. 
    } 

Answer 2

第一步是寫了一大堆

System.out.println("1"); 

來縮小問題發生。打印出一些重要變量的價值也很有幫助。

在其他的答案提到，這樣的：

boolean done = false; 

System.out.println("1"); 

while(done) { 
    System.out.println("2"); 
    ... 
} 

System.out.println("3"); 

輸出這樣的：

1 
3 

這應該是一個相當大的線索。

Answer 3

而且你指定的東西加侖，而不是時間，然後作爲一個影響你被0

Answer 4

分我可以看到你的程序可能不會運行。您遇到的問題是與while循環

boolean done = false; 

while (done){ 
    //.....code.....// 
} 

會發生什麼事是你的while循環才能運行需要一個「真」。你的設置在開始時被設置爲false，因此循環不會被執行。你可以通過這樣做來解決這個問題

boolean done = false; 

while (!done){ 
    //....code....// 
} 

那麼這是什麼「！」基本上是這樣說的：「因爲你沒有完成這個工作，所以當你完成之後不要再次進入這個循環，只是忘記它」，或多或少;

Answer 5

我調試了你的代碼，它應該現在正常工作。 試試吧。

public static void main(String[] args) 
     { 
      //Declare Class Variables 
      String highway; 
      int startMiles=0; 
      int endMiles=0; 
      int time= 0; 
      boolean done = true; 
      while (done) 
      { 
       try 
       { 
        String start = JOptionPane.showInputDialog(null,"Enter starting mileage: "); 
        startMiles = Integer.parseInt(start); 

        String end =JOptionPane.showInputDialog(null,"Enter ending mileage: "); 
        endMiles = Integer.parseInt(end); 

        if (endMiles<=startMiles) throw new Exception(); 

        String amount = JOptionPane.showInputDialog(null,"Enter total time as a decimal value: "); 
        time = Integer.parseInt(amount); 
        done = false; 
       } 
       catch(Exception e) 
       { 
        JOptionPane.showMessageDialog(null, "Your ending mileage,"+endMiles +", must be greater than your starting mileage, " + startMiles, "Error in Mileage", JOptionPane.ERROR_MESSAGE); 
       } 
      } 
      JOptionPane.showMessageDialog(null, startMiles); 
      JOptionPane.showMessageDialog(null,"Average speed is "+ (endMiles - startMiles)/time +"miles per hour."); 
     } 

Answer 6

零（加侖）

1.By分，這就是爲什麼它給「一般的速度是無限英里每小時」

在這份聲明中有一個串聯錯誤.......，「，endMiles +」， 它應該是...... 「+ endMiles +」，

JOptionPane.showMessageDialog（null，「您的結束里程數，」，endMiles +「，必須大於您的起始里程數，」+ startMiles，「里程錯誤」，JOptionPane.ERROR_MESSAGE ）;